Furthermore, little is known about the cerebral tissue oxygen saturation (SctO2) in these morbidly obese patients during laparoscopic gastric bypass surgery. Since the unexpected finding that NMB influences hypoxic ventilatory response, more research is needed into the effect of neuromuscular blockers and their reversing agents on cerebral oxygenation. Using near infrared spectroscopy (Fore-sight®) technology absolute brain tissue oxygenation can be quantified to study these effects.